The present invention relates to a method for displaying a measured value.
Instrument clusters in a motor vehicle are discussed, for example, in the document xe2x80x9cDas Porsche Informationsxe2x80x94und Diagnosesystemxe2x80x9d [The Porsche Information and Diagnostic System] from VDI Reports No. 687, 1988, in which a plurality of display instruments may be arranged as combined in one unit. In addition, displays may be provided which indicate possible malfunctions of the vehicle to a driver, such as a coolant temperature which is too high. Moreover, there are so-called freely programmable instrument clusters in which all measured quantities and warning fields may be displayed in one large screen display or projection display disposed, for example, in front of the driver. Such a screen display is discussed, for example, in the article xe2x80x9cStern der Zukunftxe2x80x9d [Star of the Future] from the periodical MOT-Technik, May 1991, page 94. Except for a situation-dependent output of warnings, as may be available from previous instrument clusters, the display in this freely programmable instrument cluster may be limited to a situation-independent presentation of measured quantities.
In contrast, an exemplary method of the present invention provides for measured values being displayed as a function of a situation, in that the display range of a measured quantity presented may be adapted to the traffic situation. This may be accomplished by ascertaining a maximum scale value from at least one further value, such as from the driving and operating data of the vehicle and/or from external or additional traffic information. While in the case of a situation-independent display of a measured quantity, the display may need to be based on an unchanging, maximum scale value, the maximum scale value in the case of a speed indicator being oriented, for example, to the maximum speed of the vehicle, the exemplary method of the present invention may permit the display range to be adapted to the respective traffic situation and the vehicle condition. Thus, the driver may be informed more accurately about the instantaneous measured value in each instance, thereby smaller fluctuations of the measured value may be more easily recognizable, as well.
Further developments and improvements of the exemplary method include the following. The measuring range may be limited with respect to the minimum value of the scale, which may apply in the case of a coolant temperature indicator. While at the beginning of the drive, a driver may be interested in how quickly the temperature rises in the lower temperature range in order, for example, to be able to switch on the vehicle heating, after a few kilometers of driving, the temperature may generally no longer fall below a value, for example, of 70xc2x0 C. Consequently, a scale range between 0xc2x0 C. and 70xc2x00 C. may be masked out, thereby permitting a range of higher temperatures to be displayed with greater accuracy.
Furthermore, in the case of driving and operating data which may require a special attention and/or action by the driver, a display of the scale may be implemented in a warning color. For example, if the display color of the coolant temperature changes into a warning color because the coolant temperature is too high, this may be indicated to the driver. Generally, the coolant temperature may lie only in a customary framework, so that a driver may not immediately observe the exceeding of a permissible value without an additional indication. With respect to the speed indicator, it may be important, for example, when driving in fog that a driver not drive faster than visibility allows. On the other hand, however, since fog may make orientation more difficult, in this case, a driver may need to rely in particular on an easily recognizable speed indicator to better estimate his/her speed. The same may hold true, for example, for driving in a tunnel or in construction site areas. Due to the additionally emphasized display of the speed scale in a warning color, the driver""s instantaneous speed may be more clearly indicated to him/her.
In a situation which requires special attention and/or action by the driver, the display of the measured-value scale may be enlarged, since better readability may also be ensured. However, the additional space needed for this purpose may be only taken up by the display as long as the special attention of the driver is deemed necessary or until the action of the driver is deemed performed. If the driver, for example, has left a road section having a special speed restriction, such as a construction site, or if the driver has filled up with gas in response to too low a tank filling, a switchover may be made again to a standard display.
The maximum scale value may be selected so that it exceeds a maximally allowed measured value by at least a first percentage value and at the most by a second percentage value, the second percentage value being selected to be greater than the first percentage value. Small exceedings of a maximally allowed measured value may thereby still be displayed in the scale. Thus, for example, slight exceedings of an allowed speed or slight exceedings of the highest speed of a vehicle measured by the manufacturer may still be represented in the display.
Moreover, at least the following measured quantities may be recorded: oil pressure, coolant temperature, generator function and outside temperature as operating parameters, because all of these measured quantities may be important either for driving safety and/or for functioning of the engine. In addition to the direct display of the operating parameters in a separate display, the operating parameters may also be used for calculating a maximum or minimum scale value of another measured quantity. This may apply in the case of the speed scale. Thus, for example, in the event of a vehicle defect such as too low an oil pressure or too high a coolant temperature, it may be desirable to not drive too fast, so that, in particular, engine damage may be avoided. When the outside temperature is in the freezing-point range, which may be ascertained by a temperature sensor, there may be increased danger of the vehicle slipping due to black ice, so that an adjusted speed of the vehicle may be applied. As already explained above, an indication to the driver may then be implemented by a speed indicator which may be enlarged, altered in color and/or detailed.
Furthermore, in the case of the vehicular speed as measured quantity, initially a position of the vehicle may be ascertained on the basis of a vehicle position finding, and from this position, the road class on which the vehicle is presently located may be determined. In this manner, it may be possible to adapt the display range, thus the minimum and maximum scale value of the speed scale, to the maximum speed allowed on this class of road. In this context, the speed scale may be adapted to maximum speeds specific to countries.
Traffic signs may be detected by a camera and, particularly in the case of traffic signs which specify the maximum speed allowed, the speed scale may be adapted to the maximum speed specified by the traffic sign.
Additional traffic information may be transmitted via a radio link to a transmitter unit, e.g. to radio beacons and/or to a Service Node. Thus, the speed indicator may be adapted to instantaneous traffic conditions. For example, a message may be transmitted to a vehicle by such a radio link, where the message may indicate that because of smog or too high a concentration of ozone, a speed restriction exists locally, the display range of the speed indicator being adjusted accordingly. In addition, local speed restrictions, for example, in a tunnel or in a construction site area, may be communicated via the radio link to the vehicle and the display range may be modified according to the speed restriction.
Moreover, the driver may be able to input a speed restriction manually, by which the display range of the speed indicator is influenced. This procedure may be particularly useful in the case of restrictions which are difficult to detect or may not be detected at all. For example, when snow chains are installed, generally a maximum speed of 50 km/h may exist. However, automatic detection of the snow chains on the wheels may be costly. In the same manner, for mud and snow tires (winter tires), a speed restriction may be valid which may reduce the maximum allowed speed of the vehicle. A manual input may make it possible to adjust the speed indicator to such a maximum speed, as well.
A display of the instrument cluster may be implemented as a liquid crystal display or as a head-up display. Both displays may require less space in a motor vehicle compared to a cathode ray tube display, and may be easy for a user of the vehicle to read.
Moreover, the processing unit may be connected or coupled to a device for audio output, so that in the case of ascertained measured values of driving and operating data which require special attention and or/an action on the part of the driver, the driver may receive an additional acoustical warning in addition to the display adapted to the situation.